1. Field of the Invention
This invention relates to a method and system for boosting the internal pressure of pressurized pipelines. In one aspect, this invention relates to a method and system for boosting the internal pressure of pressurized pipelines from inside the pressurized pipelines.
2. Background of the Invention
In the United States today, there are thousands of miles of gas pipelines that are unable to increase pressure to increase capacity to meet the increases in demand for the gas. Low pressure gas pipelines are particularly susceptible to this problem. By low pressure gas pipelines, we mean gas pipelines in which the gas pressure is in the range of inches of water column to about 2 psig. Cast iron pipeline systems are in some of the most densely populated locations in the United States. For example, in the northeastern United States, some of the largest local distribution companies (LDCs) have low pressure cast iron distribution mains that supply some of the nation's largest urban populations. These areas also have “fuel oil” (e.g. No. 4/6 fuel oil) burning boiler heating units for residential and commercial customers.
As the push to greener fuels now offers incentives at all levels to switch to a “cleaner” burning fuel, such as natural gas, the demand on the distribution mains increases. In addition, new uses of natural gas, such as for residential and commercial standby power generation, further increase the demand on the distribution mains. Unfortunately, the current low pressure systems already operate at their maximum pressure rating. This pressure rating cannot be increased as the entire system is designed to be of the same pressure required to safely operate end-use appliances. High end-use demand results in local low pressures in the gas main that can cause inadvertent shutdown of appliances. This increase in demand can especially occur during peak hours such as in the morning when hot water heater use is very high and/or after the workday during the winter months when heating/furnace system use is at its peak.
Accordingly, there is a need for a simple and automatic system that can provide a local boost gas supply (at one or multiple locations) when needed without substantially increasing the overall pressure of the system. It would be of particular benefit if the system could provide boosts in “zones” along the length of the gas main where the draw off of gas is greatest.
At present, there are no known systems in existence that completely solve this problem without major changes or wholesale replacement of the distribution pipeline. Current options include a complete tear out or abandonment of the current low pressure system and replacement with a high-pressure, regulated system and lining of the low pressure pipe with a structural liner that will support a higher pressure. The first option generally requires all service lines to be replaced and taps to be installed along with the service lines, which is either prohibitively expensive or logistically impossible. The second option has issues with bridging sharp bends, mechanical couplings, and non-full bore openings and is an expensive process that requires a very thorough cleaning prior to lining, an expensive process to reattach taps, and regulators at each residence and, possibly, replacement of the service lines to handle the higher pressures.